Essentially,
Acquired Brain Injury is an insult to the brain and can
come in many forms, including: Traumatic Brain Injury,
Closed Head Injury, Cervical Trauma Syndrome, and/or
Stroke This can produce a diminished or altered state of
consciousness, and may result in impairment of cognitive
abilities, sensory processing and /or physical function.
Impairments may be mild or severe; most are amenable to
rehabilitation.

THE THREE MOST DEVASTATING
AND INTOLERABLE VISUAL PROBLEMS RESULTING FROM BRAIN
INJURY AND STROKE

Although there are many visual
problems that arise from brain injury and stroke, three
are more devastating and impairing than the rest. These
are visual field loss, intractable double vision, and
visual / balance disorders.

Visual Field Loss

With a visual field loss the
patient is literally blind to half of their field of
vision. This places the person at increased risk of
further injury and harm from bumping into objects, being
struck by approaching objects, and falls.

A two fold approach is used to treat visual field loss.
Visual rehabilitation activities are prescribed by the
doctor and administered by the therapist to teach
scanning of the hemianopic field loss. In addition to
occupational therapy, special visual field awareness
prism lenses are used in treating visual field loss. As
the patient scans into the prism the optics are shifted
so as to perceptually gain about 15 to 20 degrees of
visual field recognition. These are used as spotting
devices only to determine if there is an object in the
periphery that deserves further visual attention. When
such an object is spotted, the patient turns their head
to view it in detail with their intact central vision.

Double Vision (Diplopia)

Double vision (diplopia) is a
serious and intolerable condition that can be seen in
patients with brain injury, stroke and other
neurologically compromising conditions. Prisms, lenses
and / or vision therapy can oftentimes help the patient
achieve fusion (alignment of the eyes) and alleviate the
diplopia. If and when these means are not employed, the
patient may adapt by suppressing the vision of one eye
to eliminate the diplopia. If lenses, prisms, and / or
therapy are not successful and the patient does not
suppress, intractable diplopia ensues.

Visual Balance Disorders

Visual balance disorders can be
caused by a Visual Midline Shift Syndrome (VMSS),
oculo-motor dysfunction in fixations, nystagmus, and
disruptions of central and peripheral visual processing.
Lenses, prisms and visual rehabilitation activities are
used in the remediation of these disorders.

Visual Midline Shift
Syndrome

Visual Midline Shift
Syndrome results from dysfunction of the ambient
visual process. It is caused by distortions of
the spatial system causing the individual to
misperceive their position in their spatial
environment. This causes a shift in their
concept of their perceived visual midline. This
will frequently cause the person to lean to one
side, forward and/or backward. It frequently can
occur in conjunction with individuals that have
had a paralysis to one side. By using specially
designed yoked prisms, the midline is shifted to
a more centered position thereby enabling
individuals to frequently begin weight bearing
on their affected side. This works very
effectively in conjunction with physical and
occupational therapy attempting to rehabilitate
weight bearing for ambulation.

Visual Hallucinations

Visual hallucinations may
occur both as formed objects like stars or other
recognizable objects or may be unformed as in
flashes and spots. The formed images may
represent misunderstanding of information in the
brain or background "noise" from the disruption
of brain tissue that is needed to process the
information.

A separate but related
cause of visual hallucinations is called Charles
Bonnet Syndrome. It occurs in patients with
significant loss of vision. The hallucinations
from Charles Bonnet Syndrome are often very
detailed such as a group of people, a truck or
an animal. These are not psychotic in nature but
simply represent the brains attempt to interpret
the impaired information and find a mental image
to match the incoming message.

Visual Neglect - Visual
Imperception

Cerebral injury from
stroke or other trauma may cause visual
imperception. It is a passive unconscious
decreased awareness of part of the field of view
or other stimuli to one side of the body. It
usually occurs with a visual field defect, but
may occur without loss of field. A person
without visual imperception, but with a visual
field loss would still be aware of the area of
loss and be more likely to make compensations. A
person with both visual field loss and visual
imperception would unconsciously neglect the
area of the field loss and thus be less likely
to compensate for the defect.

Damage to the right side
of the brain may cause both visual field loss
and visual imperception to the left side. Right
brain injury neglect is usually more severe than
left brain injury neglect. The most common site
for visual imperception is the parietal lobe,
but damage to frontal lobe and even the deeper
structure (thalamus and basal ganglia) may cause
visual imperception.

The treatment of visual
imperception is still limited. It begins with
teaching the patient to be aware of the
neglected side often through occupational
therapy. If the patient has a visual field
defect, visual field awareness prism may be
beneficial, followed by intense occupational
therapy.

Vision Related Side Effects
of Traumatic Head Injury

•Field Loss

•Hemianopsia (Loss of half of the field of
view to the right or left, or bi-nasal or bi-temporal)

•Quadranopsias ( Loss of about 1/4 sector
of the visual field)

•Central Loss

•Sector Loss

•Peripheral Loss

•Total Loss of Visual Field

•Attitudinal Losses

•Photophobia

•Reading Disorders

•Diplopia - Exotropia, Esotropia and
Hypertropia

•Cranial Nerve Paresis / Paralysis III ,IV,
VI , VII

•Small changes in refractive errors more
significant

•Nystagmus

•Lagophthalmos

•Dry Eye - Decreased Blink Rate

•Visual Hallucinations

•Anisocoria

•Accommodative Problems

•Convergence Problems

•Eye Movement Disorders, Fixation, Pursuits

•Frequent Headaches

•Unstable Ambient Vision

•Visual Perceptual Disturbances

•Disturbances in body image

•Disturbances of spatial relationships

•Right - Left discrimination problems

•Agnosia - difficulty in object recognition

•Apraxia - difficulty in manipulation of
objects

•Memory Loss

Reading Problems & Traumatic
Brain Injury

Reading problems may occur from
various problems after a stroke or head injury. It is
crucial that the type of reading problem be diagnosed.
The list below contains some of the more common causes
of reading problems after brain injury with introduction
to how they may be treated. The problems may occur
individually or be part of a constellation of problems
related to Post Trauma Vision Syndrome. Treatment of
PTVS through various neuro-optometric rehabilitative
interventions may resolve many of the problems below.

Post Trauma Vision Syndrome

Essentially, individuals with PTVS
begin to look at paragraphs of print almost as isolated
letters on a page and have great difficulty organizing
their reading ability. It has been found that the use of
prisms and bi-nasal occlusion can effectively
demonstrate functional improvement, while also being
documented on brain wave studies by increasing the
amplitude (this is like turning up the volume on your
radio).

Reading Problems Due to Visual Field Loss

Field loss patients often lose
their place in reading. Simple techniques, like boundary
marking, sticking a Post-it note along the side of a
column of print, can mark the beginning or end of the
column and reduce confusion.

Convergence Disorders Affecting
Reading

Patients may experience reduced
convergence after stroke or head injury. Our eyes must
turn in together accurately as a team to prevent double
vision and eye fatigue in reading. Prisms may aid some
patients. Orthoptic therapy may aid some, but not all
patients with convergence insufficiency will respond
fully to therapy due to the variation in the extent of
trauma which may be present.

Loss of Accommodation (Focusing)
Affecting Reading

Young head injury patients may
experience decreased focusing ability. It is often
missed because at an early age doctors don't expect loss
of accommodation. It happens naturally at about age 42.
Individual with reduced accommodation may benefit from
bifocals.

Alexias /Word Blindness
Affecting the Ability to Read

If the patient is unable to read
due to damage to areas which process reading, but can
understand verbal reading, electronic machines are
available that scan all typed print, interpret it and
read it aloud to the patient. Talking books and reading
radio are also very helpful.

Loss of Cognitive Skills May
Affect Reading and Comprehension

Patients may need to relearn their
reading skills developed in childhood or the damage may
be so severe as to preclude reading. Therapists may be
able to re-establish reading over time. Low Vision
Causing Reading Problems When visual acuity is
significantly impaired, high add bifocals or low vision
devices may be indicated. Magnifiers, Electronic
Magnification CCTVs, special and microscopic eye wear
may help the patient read again.

Diplopia Causing Disruptions to
Reading

If the binocular vision problem can
be treated, therapy, surgery or prisms may be used to
re-establish binocular vision. If the double vision is
not curable, then occlusion may be required. Partial
semi-opaque occlusion may reduce diplopia while
minimizing the disruption to ambient vision caused by
total opaque.

Eye Gaze Disorders

Patients with inferior gaze paresis
may not be able to look down into the bifocal, but may
read with single vision reading eyewear.

Eye Movement /Tracking Disorders
Affecting Reading

Eye movement disorders may also
interfere with reading. As we read down a line of words,
we must make a series of accurate jumps from one group
of words to another. As our head or the paper moves, we
must make rapid adjustments of our eye position. These
rapid eye movements are mediated by the vestibular
system.

Unstable Ambient Vision

Brain injury patients may present
with vertigo, sensitivity to light and extreme
sensitivity to motion around them. Trying to sustain
reading becomes very difficult. The patient may
experience nausea, loss of attention, difficulty
fixating on the words and fatigue. Unstable ambient
vision is a hallmark of Post Trauma Vision Syndrome.

Light Sensitivity after Brain
Injury

Brain injury is often accompanied
by increased light sensitivity and general inability to
tolerate normal glare. The problem seems to be an
inability of the brain to adjust to various levels of
brightness. It is as if one had a radio and the volume
control was broke and you could not make the adjustments
you normally do to control loudness.

Dry Eye Syndromes and Altered Tear / Lid Function

Our eyelids work much like the
windshield wipers on our cars. The lids wipe across our
cornea cleaning it and constantly restoring a new layer
of tear film. If the cornea is not kept moist, a dry eye
may develop. It is much like chapped lips and leads to
dry, burning, gritty eyes. After brain injury, the rate
of blinking may slow and the completeness of the blinks
may decline. The patient may be making only occasional
partial blinks. This leaves the lower portion of the
cornea to dry and become uncomfortable. The simple
addition of artificial tears and reminders to the
patient to blink fully and frequently can manage this
problem. In severe cases, silicone tear duct plugs may
inserted to reduce the loss of tears from the eye down
the normal draining tubes.

Balance & Illusions of
Movement

Dizziness and Balance Problems Related to Vision

Vision plays a significant role in
balance. Approximately twenty percent of the nerve
fibers from the eyes interact with the vestibular
system. There are a variety of visual dysfunctions that
can cause, or associate with dizziness and balance
problems. Sometimes these are purely visual problems,
and sometimes they are caused from other disorders such
as stroke, head injury, vestibular dysfunction,
deconditioning, and decompensation.

Visual Dysfunctions
Causing Dizziness and Balance Problems

Aneisokonia

Aneisokonia is a condition where an
excessive difference in prescription between the eyes
causes a significant difference in magnification of
images seen between the eyes. When this magnification
difference becomes excessive the effect can cause
disorientation, eyestrain, headache, and dizziness and
balance disorders. Treatment is with contact lenses, or
special magnification size matched lenses called
isokonic lenses.

Vertical Imbalance

Normally the eyes work in perfect
synchrony. However, following trauma, fever, stroke,
deconditioning, or sometimes for no apparent reason, one
eye will aim higher than the other will. When mild and
not enough to cause double vision this is called
hyperphoria. If excessive to the point of causing double
vision, it is termed hypertropia. In an effort to adjust
to the vertical misalignment of the eyes, the person
will frequently tip their head to mechanically help
align the eyes. This in turn can cause disorders in the
fluid of the inner ear and resultant dizziness and
balance disorders. Treatment is with therapy to correct
the muscle imbalance and prisms.

Binocular Vision Dysfunction

Binocular vision refers to how the
eyes work together as a team. It is the coordination of
convergence and divergence (eye teaming and alignment)
with accommodation (focusing). Following trauma, fever,
stroke, deconditioning, or sometimes for no apparent
reason dysfunctions can occur causing the eyes to be
weak or overactive. When this occurs, the eyes will
manifest a tendency to drift outwards or inwards. This
in turn can cause eyestrain, double vision, muscle spasm
and excessive peripheral visual stimulation, which in
turn can trigger dizziness and balance problems.
Treatment is with lenses, prisms and therapy.

Double Vision

Double vision is among the most
disorienting and devastating vision disorders. People
suffering from double vision will often times go to
great lengths to alleviate the double image because it
is so bothersome. Many will actually even patch, or
cover an eye, thereby eliminating the vision from one
eye just to get rid of their double vision. Double
vision is caused when the two eyes do not align, or work
together and one eye actually turns out, in, up, or down
compared to the fellow eye. The overall encompassing
term for this is strabismus. The disorientation from
double vision will frequently trigger dizziness and
balance problems. Treatment is with lenses, prisms,
therapy, partial selective occlusion and rarely surgery.

Ambient Visual Disorder

The ambient visual process
frequently becomes dysfunctional after a neurological
event such as a Traumatic Brain Injury (TBI) or Cerebral
Vascular Accident (CVA). Persons can often have visual
symptoms that are related to dysfunction between one of
two visual processes: ambient process and focal process.
These two systems are responsible for the ability to
organize oneself in space for balance and movement, as
well as to focalize on detail such as looking at a
traffic light. Distortions of the spatial system may
cause an individual to misperceive their position in the
environment. This in turn can cause dizziness and
balance problems with the person showing a tendency to
lean to one side, forward and/or backward. Treatment is
with specially designed prisms and partial selective
occlusion. These techniques work effectively in
conjunction with physical and occupational therapy
attempting to rehabilitate weight bearing for
ambulation.

Eye Movement Disorders

Eye movement disorders typically
show up as instability of visual gaze (nystagmus),
jerkiness of pursuits (eye tracking), or jerkiness of
saccades (visual scanning). Eye movement disorders may
be congenital, or acquired. When acquired, some of the
typical causes are brain injury, stroke, vestibular
dysfunction, multiple sclerosis, and other neurological
disease or disorder.

When there is an acute adult onset of nystagmus the
brain does not register that it is the eyes that are
shaking. Rather, the brain interprets that it is the
world and objects in it that are moving. This is called
oscillopsia and will frequently cause dizziness and
balance problems.
As always, treatment is first aimed at correcting (if
possible) the underlying cause for the nystagmus, or
other eye movement disorder. Concurrently, the following
neuro-optometric rehabilitation approaches may be
helpful.

If there is diplopia, prism, and/or partial selective
occlusion is indicated. Visual exercises may also help
expand the range of single binocular vision. Head
position and direction of gaze may help compensate for
the oscillopsia by finding a null point where the
nystagmus is decreased. Partial selective occlusion can
be helpful where (typically) the nasal or temporal
aspect of the lenses in eyeglasses is partially
occluded with tape. A centimeter or less is usually
sufficient. Nasal occlusion helps improve peripheral
ambient vision, and temporal occlusion helps block
peripheral stimulation. Low amounts of base-in prism can
also help stabilize peripheral vision and thereby help
the oscillopsia.

Accommodative (Focusing) Problems

To change our focus from distance
viewing to near for reading, our brain must interpret
how far away the object in space is located and then
send a signal to the ciliary muscle inside our eye
causing it to change the shape of the crystalline lens
to exactly focus for that distance.

Our focusing ability is greatest in childhood and
progressively declines throughout most of our life until
after age forty, the focus has declined to require
reading lenses or bifocals. Trauma to the brain may
reduce the ability to focus accurately in young people
and may lead to the need for reading correction or
bifocals. Spasms of accommodation may occur causing over
focusing and may present as a temporary increase in
myopia.